Method of producing embossing foils



Nov. 24, 1936. K, KU'RZ 2,062,226

METHOD OF PRODUCING, EMBOSSING FOILS Filed June 6, 1952 J'NVENTORPatented Nov. 24, 1936 UNITED STATES PATENT OFFICE Konrad Kurz, Furth,Germany, assignor to Diamond Decorative Leaf 00., Stapleton, StatenIsland, N. Y.

Application June 6, 1932, Serial No. 615,660 In Germany June 13, 1931 3Claims.

Gold leaf is gold beaten to very thin leaves.

The gold beating work is very expensive, and

the thinness of the leaf and therefore the saving in gold is limited bythe'production of por- 5 ous portions of the leaves through which theembossed article might become visible.

In order to do away with the tedious and expensive gold beating and tosave gold, it has already been proposed to produce a gold depositelectrolytically on bright polished metal plates or bands in a goldbath. This deposit or coating is of uniform thickness throughout and itis possible, in order to save gold, to make it so thin that it is justsumcient to prevent the embossed article being visible. In order to beemployed as embossing foil, this deposit, however, must be stripped fromthe metal plates or bands and the uniform stripping of the dried depositis a difficult operation which may often cause trouble.

In order to obtain the gold strips separately, it has also been proposedto electrolytically deposit on a silver band brushing over the surfaceof the gold bath and to dissolve the silver band by passing the doubleband over the surface of a nitric acid bath. It is evident, that thisdoes not present considerable advantages as compared with the goldbeating. 7

According to the invention an embossing foil is obtained by chemicallyproducing a mirror coating on one of the known, smooth supports capableto be embossed in sheet or band form, for example of paper, cellophaneor similar film masses, and by grounding the mirror coating in knownmanner.

Embossing foils can be produced in this manner by means of all mirrorforming metals, such as gold, silver and platinum. Glassine paper,cellophane or similar film masses may be employed as supports,cellophane being preferred. If a silver embossing foil is to beobtained, silver is precipitated on the cellophane from an ammoniacalsolution of silver nitrate by means of reducing salts, Rochelle salt forinstance, as known in precipitating a silver coating on to a glassplate. To ground the mirror coating, shellac, Zapon lacquer or the likemay be used, as for grounding the layer of bronze powder embossingfoils. v

The production of such an embossing foil by direct chemical productionof a mirror coating on the support is cheaper, simpler and more reliablethan one with beaten or electrolytically precipitated metal leaf andgivesembossings, the brightness of which is far superior than those of 5the two other types. The production of the new foil can as is apparent,be effected, similarly to the production of the mirror surface on theback of a glass plate, with the difference that instead of the glass 2.flexible, exceedingly thin film as smooth as possible is employed, fromwhich film 5 the mirror coating, owing to its greater adhesion to thegrounding, can be detached during the stamping process under theinfluence of the heat of the die. The detaching may be facilitated byinterposing a suitable fusible layer,.for exam ple of soft resin orcellophonium, between the mirror coating and the support, but this isnot necessary if it is not desired to colour the interposed fusiblelayer in order thereby to change the color of, for example a whitemirror coating.

Smooth cellulose films in the form of so called Cellophanes, Ce11it" andthe like have already been employed as supports for the fusible layerand the beaten leaves. This measure, however, does not anticipate theinvention because the 20 invention first proposes to chemically providesuch films with a mirror coating and then to apply a grounding layer onto these deposits for obtaining an embossing foil, and patent protectionis only sought for the combination of these two measures.

It has further been proved that the embossing is the brighter andsharper the thinnerthe metal deposit is made. The new method ofproducing the embossing foils is also far superior to the known methodsof production as regards the saving in precious metals, especially gold,platinum or silver. I

The new embossing foil is illustrated in the accompanying drawing inwhich: 35

Fig. 1 is a perspective view of a foil without a fusible layer, and

Fig. 2 is a similar view of a foil with a fusible layer.

With reference to Fig. 1, a is the smooth support capable of beingembossed, b the chemically precipitated mirror coating and c thegrounding layer or sizing. According to Fig. 2, a fusible layer d isinterposed between a and b.

1. Method for producing an embossing foil the metal layer of which istransferred by the heat of the embossing die from its carrier on to theob-' ject to be embossed, consisting in chemically producing a mirrorcoating on a flexible smooth film support capable of being embossed andin grounding this mirror coating on the outer side.

2. Method for producing an embossing foil the metal layer of which istransferred by the heat of the embossing die from its carrier on to theobject to be embossed, consisting in coating a flexible smooth filmsupport capable of being embossed with a layer of fusible material, andin chemically reducing a precious metal onto this fusible layer, and ingrounding this mirror coating on the outer side.

KONRAD KURZ.

